June 9, 1938: Huang He Diversion: Largest Act of Environmental Warfare in History

The Huang He (Yellow River) has been called “China’s Sorrow.” The name pays tribute to the millions killed by the river’s churning, muddy waters in a long history of dramatic diversions and massive floods. One of the most notable recent events in the river’s troubled history occurred in June 1938, when the Nationalist Chinese Army diverted the river to block invading Japanese troops. In both number of deaths and geographic scale, this event was the largest act of environmental warfare in modern history.

The story of the diversion begins with the railroads, says Steven Dutch, a geologist at the University of Wisconsin at Green Bay. In July 1937, Japan moved troops into China and began seizing power in the northern territories, beginning the Second Sino-Japanese War. By June of the next year, Japanese troops had moved inland from occupied Shanghai to Nanjing, Xuzhou and Kaifeng. Though many maps of the invasion show Japanese control was widespread across these regions, Dutch says that Japanese effective control was mostly along the rail corridor. In other areas, Japanese power was less homogenous, interrupted by large areas controlled by Chinese troops, guerilla groups or bandits.

After Kaifeng, the next stop along the railroad was Zhengzhou, Dutch says. This was the last major rail station before the Japanese could move south and attack Wuhan — the most important city politically and militarily in central China. Chinese General Chiang Kai-shek desperately needed to end Japan’s deadly march inland. And so the Chinese military turned to the deadliest force within reach — the Huang He.

The Huang He flows east out of the Chinese highlands across a plateau of loess, or fine sediment, just northwest of Kaifeng. From this point, the river meanders across a huge, flat alluvial fan. To the north and south of the current channel stretch the long fingers of older abandoned river channels, now empty or filled with smaller rivers. The Huang He has flowed in at least nine different channels in the last 2,000 years, on both sides of the Shandong Peninsula. For scale, Dutch says, imagine the Mississippi River shifting back and forth between western Texas and the Florida panhandle.

The enormous annual sediment load of the Huang He (providing the characteristic yellow color of the Yellow River) has complicated human efforts to control the river’s course through levees. These structures have been raised higher and higher to keep pace with the bottom of the river as it rises from sediment fill. As a result, by the summer of 1938, the river reach between Kaifeng and Zhengzhou flowed significantly above the surrounding land. This, combined with its position at the top of the alluvial fan, made the river here extremely favorable for diversion.

General Chiang Kai-shek knew that by breaking the levees and diverting the river south into an older channel, he could effectively cut off the Japanese rail route to Zhengzhou, Dutch says. This strategy was not entirely new. Previous military destruction of the levees had helped armies in the area in A.D. 1129 and 1642. The Chinese hoped that a similar strategy would turn the military conflict in their favor and protect the heartland of China from the Japanese.

Unfortunately, the decision took a great civilian toll and had only moderate military success. Official Chinese estimates suggest that nearly 800,000 Chinese civilians died. Even more were forced to flee from their homes. Militarily, the Japanese suffered only minor losses of troops and materials. Although the Chinese did gain time to relocate their wartime capital — which had been moved to Wuhan after the fall of Nanjing earlier in the invasion — within three months, Wuhan fell under Japanese control.

Though little detailed information on the effects of the flooding is available, similar events suggest the kind of destruction the people living near the Huang He probably experienced in 1938, Dutch says. As the enormous volume of the Huang He rushed down into one of the smaller, quieter rivers occupying the old channel, the riverbanks could do little to hold the waters from spilling out into the broad floodplain, destroying crops and killing thousands in its path. Once the worst of the flooding subsided, waterborne diseases likely added more fatalities.

Dutch suggests that one way to put the number of deaths in perspective is population density. The fatalities were significant, but this is understandable considering the huge number of people living in areas impacted by the flood. Even though China had four times fewer people in 1938 than live there today, the at-risk population was still huge — nearly 15 million.

“Big floods are a fact of life in China,” Dutch notes, and considering that there are now more people than ever in the region, it’s easy to wonder whether a similar disaster awaits them today. But an event such as the 1938 flood is less likely today, he says. Twenty-first century geologists and disaster management officials in China have a much better understanding of river dynamics and the impact of floods. China also has a better infrastructure for issuing warnings, initiating rescue operations and supporting relief efforts. Additionally, the fatalities in 1938 were higher because the disaster occurred during war, when the country’s infrastructure was already unstable.

One thing is certain: Human intervention cannot forever halt the natural cycle of river change on the Huang He. Dutch says that although the Chinese system of levees may work fine for the near future, “no levee will hold the river in one place indefinitely.”

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